Varroa Mite Infestation Research Articles

Molecular Assessment of Genes Linked to Immune Response Traits of Honey Bees in Conventional and Organically Managed Apiaries.

Simple SummaryHoney bees play a critical role in agriculture as they provide pollination services to many agricultural crops. However, honey bee populations continue to decline due to exposure to pesticides, habitat destruction, pests, diseases and beekeeping practices. In this study, we assessed selected biological parameters associated with honey bee health in two beekeeping practices (organic and conventional). We compared total protein content in young worker bees from organically and conventionally managed apiaries. We also assessed differential gene expression at two levels of Varroa mite infestations (0% and 5%) in selected genes involved in nutrition and cellular defense (vitellogenin (Vg), malvolio (Mvl), prophenoloxidase (PPO)-, genes involved in lifespan (superoxide dismutase (Sod 1), superoxide dismutase 2 (Sod2)) and immune function genes (immune deficiency (Imd), spaetzle (Spz). Total soluble protein in young adult worker bees was similar in both beekeeping practices. The genes PPO, Vg and Mvl were upregulated in young adult bees with no mite infestations from organically managed apiaries and could mount an immune response through Spz and Sod 1 when challenged by 5% Varroa mite infestation levels. Overall, these findings provide useful insights into the genetic response of honey bees under two beekeeping practices and could help improve honey bee health.Honey bees are of great economic importance, not only for honey production but also for crop pollination. However, honey bee populations continue to decline mainly due to exposure to pesticides, pathogens and beekeeping practices. In this study, total soluble protein was measured, total RNA was extracted and first-strand cDNAs were generated. Quantitative PCR was used to assess the relative expression (transcript abundances) of immune function-related genes in honey bees collected from organically and conventionally managed hives. Honey bees collected from conventionally managed hives with 0% Varroa mite infestation levels displayed an upregulated expression of the prophenoloxidase gene (cellular defense). Similarly, honey bees collected from organically managed hives had increased levels of the vitellogenin gene (immune function and longevity). The gene expression for malvolio (sucrose responsiveness) was highest in organically managed hives with 0% Varroa mite infestations. Young adult bees collected from organically managed hives with 5% Varroa mite infestation levels had upregulated expressions of the gene spaetzle, whereas bees from similarly infested, conventionally managed hives did not, suggesting that honey bees from organically managed hives could mount an immune response. In young adult bees collected from organically managed hives only, the expression of the immune deficiency gene (antimicrobial defense) was upregulated. The relative gene expression for superoxide dismutase 1 increased in young adult bees collected from hives with 5% Varroa mite infestation levels as expected. However, for superoxide dismutase 2, there was a high level of gene expression in adult bees from both conventionally managed hives with 0% Varroa mite infestation levels and organically managed hives with 5% Varroa mite infestations. The gene CYP9Q3 (pesticide detoxification) that metabolizes coumaphos and fluvalinate was upregulated in adult bees collected from organically managed bees. Overall, these findings provide useful insights into the genetic response of honey bees to some environmental stressors and could be an important component of best beekeeping practices that intend to enhance honey bee health.

Evaluating the impact of jatropha oil extract against the Varroa mite, Varroa destructor Anderson & Trueman (Arachnida: Acari: Varroidae), infesting honeybee colonies (Apis mellifera L.)

The Varroa mite, Varroa destructor Anderson & Trueman (Arachnida: Acari: Varroidae), is a severe external parasitic mite of honeybees that causes great losses of colonies globally. Four concentrations (1, 2%, 5, and 10%) of Jatropha curcas oil were tested for controlling the Varroa mite. Significant effects of reducing percentage of the mite infestation (P = 0.05) after second treatment for sealed brood and after third treatment for adult workers in all tested concentrations of J. curcas were recorded. The low concentrations 1 and 2% of J. curcas were more effective than the higher ones 5 and 10% on reduction of percentage of Varroa mite infestation. Moreover, the colonies treated with the lowest concentrations of jatropha oil had the highest amount of brood area (75.75 and 77.50 inch2) and the highest number of combs covered with bees compared with the colonies treated with the concentrations 5 and 10%. Treated colonies with the concentrations 1, 10, and 5% had a high amount of stored honey and pollen grains, 126.50, 111, and 96 inch2 and 11.25, 9.75, and 9.75 inch2, respectively. Obtained results encourage researchers to study deeply the ability of using jatropha oil in the widely field of Apicultural.

Diagnosis of Varroa Mite (Varroa destructor) and Sustainable Control in Honey Bee (Apis mellifera) Colonies—A Review

Determining varroa mite infestation levels in honey bee colonies and the proper method and time to perform a diagnosis are important for efficient mite control. Performing a powdered sugar shake or counting mites that drop from combs and bees onto a hive bottom board are two reliable methods for sampling varroa mite to evaluate the efficacy of an acaricide treatment. This overview summarizes studies that examine the efficacy of organic acids and essential oils, mite monitoring, and brood interruption for integrated varroa mite control in organic beekeeping.

Health status of honey bee colonies (Apis mellifera) and disease-related risk factors for colony losses in Austria.

Austrian beekeepers frequently suffered severe colony losses during the last decade similar to trends all over Europe. This first surveillance study aimed to describe the health status of Austrian bee colonies and to analyze the reasons for losses for both the summer and winter season in Austria. In this study 189 apiaries all over Austria were selected using a stratified random sampling approach and inspected three times between July 2015 and spring 2016 by trained bee inspectors. The inspectors made interviews with the beekeepers about their beekeeping practice and the history of the involved colonies. They inspected a total of 1596 colonies for symptoms of nine bee pests and diseases (four of them notifiable diseases) and took bee samples for varroa mite infestation analysis.The most frequently detected diseases were three brood diseases: Varroosis, Chalkbrood and Sacbrood. The notifiable bee pests Aethina tumida and Tropilaelaps spp. were not detected. During the study period 10.8% of the 1596 observed colonies died. Winter proved to be the most critical season, in which 75% of the reported colony losses happened. Risks for suffering summer losses increased significantly, when colonies were weak in July, had queen problems or a high varroa mite infestation level on bees in July. Risks for suffering winter losses increased significantly, when the colonies had a high varroa mite infestation level on bees in September, were weak in September, had a queen older than one year or the beekeeper had few years of beekeeping experience. However, the effect of a high varroa mite infestation level in September had by far the greatest potential to raise the winter losses compared to the other significant factors.

The Dynamics of Deformed Wing Virus Concentration and Host Defensive Gene Expression after Varroa Mite Parasitism in Honey Bees, Apis mellifera.

The synergistic interactions between the ectoparasitic mite Varroa destructor and Deformed wing virus (DWV) lead to the reduction in lifespan of the European honey bee Apis mellifera and often have been implicated in colony losses worldwide. However, to date, the underlying processes and mechanisms that form the multipartite interaction between the bee, mite, and virus have not been fully explained. To gain a better understanding of honey bees’ defense response to Varroa mite infestation and DWV infection, the DWV titers and transcription profiles of genes originating from RNAi, immunity, wound response, and homeostatic signaling pathways were monitored over a period of eight days. With respect to DWV, we observed low viral titers at early timepoints that coincided with high levels of Toll pathway transcription factor Dorsal, and its downstream immune effector molecules Hymenoptaecin, Apidaecin, Abaecin, and Defensin 1. However, we observed a striking increase in viral titers beginning after two days that coincided with a decrease in Dorsal levels and its corresponding immune effector molecules, and the small ubiquitin-like modifier (SUMO) ligase repressor of Dorsal, PIAS3. We observed a similar expression pattern for genes expressing transcripts for the RNA interference (Dicer/Argonaute), wound/homeostatic (Janus Kinase), and tissue growth (Map kinase/Wnt) pathways. Our results demonstrate that on a whole, honey bees are able to mount an immediate, albeit, temporally limited, immune and homeostatic response to Varroa and DWV infections, after which downregulation of these pathways leaves the bee vulnerable to expansive viral replication. The critical insights into the defense response upon Varroa and DWV challenges generated in this study may serve as a solid base for future research on the development of effective and efficient disease management strategies in honey bees.

Field evaluation of Maqs® and Api-Bioxal® for late summer control of Varroa mite infestation in Northeastern Italy

The study evaluates the efficacy and effects of two organic acid-based miticides (Maqs® and Api-Bioxal®) used in late summer to reduce the population of Varroa destructor mites in colonies of Apis mellifera ligustica. The study took place in Albaredo d’Adige (Verona, Northeastern Italy). Twenty-six honey bee colonies, divided into four groups, were used for the experiment. Miticide efficacy, average daily mortality rate of adult bees, and number of bees present in the hives at specific timeframes were evaluated. The average daily efficacy of Maqs®’s miticide proved to be 96.8% compared to 93.4% for Api-Bioxal® combined with queen caging. High adult honey bee mortality was recorded after treatment with Maqs®, showing that average daily mortality was 82.4% higher than natural daily mortality. Daily mortality for Api-Bioxal® and queen caging was instead 30.1% lower than in non-treated colonies. The average decrease in the colony population of the treated groups was higher in the Maqs® (–38%) than in the Api-Bioxal® group (–28%). The fall in the latter was comparable to the values recorded in the control groups (–23% in the Api-Bioxal and –24% in the Maqs® control groups). Both veterinary medicinal products were effective for the control of V. destructor mite populations in late summer. However, the important negative effects recorded in the Maqs® group discourage the use of this miticide in geographical and climatic conditions of the type described in this study. Api-Bioxal® in combination with queen caging did instead confirm its efficacy and reliability for controlling the infestation in Northeastern Italy.

Thorough morphological and genetic evidence confirm the existence of the endemic honey bee of the Maltese Islands Apis mellifera ruttneri: recommendations for conservation

The status of Apis mellifera ruttneri, an endemic honey bee of the Maltese islands, was uncertain after a series of devastating Varroa mite infestations followed by ill-conceived replacement programs. Morphometric analysis, which was the method originally used to identify this honey bee subspecies, was carried out using 33 different parameters. Thirty-two colonies exhibiting morphometric data that corresponded to those in the original description of A. m. ruttneri were identified (p > 0.99). In addition, the mitochondrial DNA region spanning the tRNAleu-Cox2 region from colonies bearing the morphometric data associated with A. m. ruttneri was amplified (77% showed the P0QQ structure). The data presented confirm morphometric similarity with A. m. siciliana and A. m. intermissa. We report the presence of A4, A8 and A9 haplotypes in A. m. ruttneri (83%; frequency 0.189, 0.081 and 0.486 respectively). European haplotypes belonging to the C1, C2 and M7 haplotypes were also recorded (17%; 0.135, 0.081, 0027). Recommendations for the conservation of this honey bee are proposed.

Using drone brood in the control of the Varroa disease of bees in Greece

The use of drone brood to control the Varroa disease (Varroa jacobsoni Ouds) was tested in twenty bee colonies (ten as control) which had a very low Varroa mite infestation. The experiment started in winter 1981-82. Early in spring 1983 the brood was removed from ten hives and later during April, May and June it was replaced by drone combs (trap combs) which were also removed when drone cells were capped. The same treatment was repeated during spring 1984. In July 31, 1984, the adult bee infestation was 0 to 7%, while the worker brood’s infestation was 0 to 17%. The data show that, after two and half years without any acaricidal treatment, six out of the ten bee colonies continued to have a very low mite infestation, while three showed high infestation and had to be treated with acaricide. One of the three colonies was treated by acaricide in the winter 1983-84, that is two years from the beginning of this experiment. On the contrary, in the ten control colonies (with the same low infestation in spring 1982) the mite infestation reached catastrophic levels by August 1983.

Influence of Varroa Mite (Varroa destructor) Management Practices on Insecticide Sensitivity in the Honey Bee (Apis mellifera).

Since Varroa mites may cause devastating losses of honey bees through direct feeding, transmitting diseases, and increasing pathogen susceptibility, chemical and mechanical practices commonly are used to reduce mite infestation. While miticide applications are typically the most consistent and efficacious Varroa mite management method, miticide-induced insecticide synergism in honey bees, and the evolution of resistance in Varroa mites are reasonable concerns. We treated colonies with the miticide amitraz (Apivar®), used IPM practices, or left some colonies untreated, and then measured the effect of different levels of mite infestations on the sensitivity of bees to phenothrin, amitraz, and clothianidin. Sensitivity to all insecticides varied throughout the year among and within treatment groups. Clothianidin sensitivity decreased with increasing mite levels, but no such correlation was seen with phenothrin or amitraz. These results show that insecticide sensitivity is dynamic throughout the 5 months test. In-hive amitraz treatment according to the labeled use did not synergize sensitivity to the pesticides tested and this should alleviate concern over potential synergistic effects. Since IPM practices were largely ineffective at reducing Varroa mite infestation, reliance on chemical methods of Varroa mite management is likely to continue. However, miticides must be used judiciously so the long term effectiveness of these compounds can be maximized. These data demonstrate the complex and dynamic variables that contribute to honey bee colony health. The results underscore the importance of controlling for as many of these variables as possible in order to accurately determine the effects of each of these factors as they act alone or in concert with others.

Environment or beekeeping management: What explains better the prevalence of honey bee colonies with high levels of Varroa destructor?

Varroa destructor is one of the major threats to honey bee colonies. The mite abundance in the colonies is affected by environmental conditions as well as by beekeeping management. The aim of this study was to recognize the main drivers associated with autumn V. destructor infestation in honey bee colonies when different regions from Argentina are compared. A total of 361 colonies distributed in five Argentinean eco-regions were examined to evaluate Varroa mite infestation rate during autumn and Nosema sp. presence. Regions were different regarding annual temperature, precipitation and especially vegetation landscape. In addition, beekeeping management practices were obtained from a checklist questionnaire answered by the beekeepers. The prevalence of colonies with high infestation level was lower in semi-arid Chaco followed by humid and transition Chaco regions. Also, colonies that were positive for Nosema sp. showed a higher Varroa infestation rate. The “environmental” effect was stronger compared with the influence of secondary drivers associated with beekeeping activities. As well, a significant association between V. destructor infestation rates and Nosema presence was identified. Under contrasting natural conditions, environment seems a predominant driver on Varroa destructor infestation level in honey bee colonies.

Migration Effects on Population Dynamics of the Honeybee-mite Interactions

Honeybees are an amazing and highly beneficial insect species that play important roles in undisturbed and agricultural ecosystems. Unfortunately, honeybees are increasingly threatened by numerous factors, most notably the parasitic varroa mite (Varroa destructor Anderson and Trueman). A recent field study showed that migrations of mites into hives on foraging bees greatly contributes to the rapid growth of mite population in colonies, and increases the mortality of honeybees. Motivated by this, we propose a simple two-patch honeybee-varroa model to explore how foraging behavior of honeybees in the presence of varroa mite infestations affect the population dynamics of honeybees and mites, respectively. We provide a full analysis on the local and global dynamics of our proposed two-patch model, which incorporates mite migration generated by honeybee foraging activities. Our analytical and numerical studies reveal the dynamical outcomes of migration including: (a) Mite's extinction cannot be prevented by mite migration when mite population in each patch goes extinct in the absence of mite migration, however, mite migration could drive mite extinct under proper conditions. (b) Under proper conditions, high rates of mite migration could have the following effects: (1) save one honeybee colony from collapsing when both honeybee colonies are going extinct without migration; (2) drive honeybee extinct in at least one patch. (c) Intermediate migration rate could generate multiple locally stable honeybee-mite coexistence equilibria, and drive mite's extinction under proper environments. (d) An increase in migration rate causes a growth of the varroa population, which in return has a negative feedback on the colony population. (e) Increasing mite migration from a healthy patch to a collapsing patch could reduce the extinction time in the collapsing patch. Our results provide novel insights on the effects of foraging and Varroa migration on colony survival.

Effects of Imidacloprid and Varroa destructor on survival and health of European honey bees, Apis mellifera.

There has been growing concern over declines in populations of honey bees and other pollinators which are a vital part to our food security. It is imperative to identify factors responsible for accelerated declines in bee populations and develop solutions for reversing bee losses. While exact causes of colony losses remain elusive, risk factors thought to play key roles are ectoparasitic mites Varroa destructor and neonicotinoid pesticides. The present study aims to investigate effects of a neonicotinoid pesticide Imidacloprid and Varroa mites individually on survivorship, growth, physiology, virus dynamics and immunity of honey bee workers. Our study provides clear evidence that the exposure to sublethal doses of Imidacloprid could exert a significantly negative effect on health and survival of honey bees. We observed a significant reduction in the titer of vitellogenin (Vg), an egg yolk precursor that regulates the honey bees development and behavior and often are linked to energy homeostasis, in bees exposed to Imidacloprid. This result indicates that sublethal exposure to neonicotinoid could lead to increased energy usage in honey bees as detoxification is a energy-consuming metabolic process and suggests that Vg could be a useful biomarker for measuring levels of energy stress and sublethal effects of pesticides on honey bees. Measurement of the quantitative effects of different levels of Varroa mite infestation on the replication dynamic of Deformed wing virus (DWV), an RNA virus associated with Varroa infestation, and expression level of immune genes yields unique insights into how honey bees respond to stressors under laboratory conditions.

Investigating the influence of postcapping period on varroa mite infestation

The aim of this study was to assess infestation levels of Varroa destructor in some honey bee colonies from the National breeding program in the central part of Iran, and the relationship between mite infestation levels and postcapping period (PCP) of worker brood cells. Shortening the PCP is an important parameter limiting the success of varroa mite reproduction in honey bee colonies. In the present study, four pure-bred line colonies from isolated areas were selected to investigate the brood capping durations and mite infestation levels. Cages were used to synchronize egg laying of the queens and the time of capping and emerging of the brood cells was recorded at two-hour intervals. The results did not show any significant differences on the average of PCP of brood cells and mite infestation levels among test colonies. In addition, non-significant correlations were found between mite infestation and the capping period during the experiment. A relatively shorter capping period of brood cells was observed in one of the provinces compared to others, corresponding with slightly lower mite levels in the same colonies, which might suggest that reducing capping duration may be one of the factors which can potentially affect mite populations in honey bee colonies and therefore should be considered in breeding programs.

Intensively Cultivated Landscape and Varroa Mite Infestation Are Associated with Reduced Honey Bee Nutritional State.

As key pollinators, honey bees are crucial to many natural and agricultural ecosystems. An important factor in the health of honey bees is the availability of diverse floral resources. However, in many parts of the world, high-intensity agriculture could result in a reduction in honey bee forage. Previous studies have investigated how the landscape surrounding honey bee hives affects some aspects of honey bee health, but to our knowledge there have been no investigations of the effects of intensively cultivated landscapes on indicators of individual bee health such as nutritional physiology and pathogen loads. Furthermore, agricultural landscapes in different regions vary greatly in forage and land management, indicating a need for additional information on the relationship between honey bee health and landscape cultivation. Here, we add to this growing body of information by investigating differences in nutritional physiology between honey bees kept in areas of comparatively low and high cultivation in an area generally high agricultural intensity in the Midwestern United States. We focused on bees collected directly before winter, because overwintering stress poses one of the most serious problems for honey bees in temperate climates. We found that honey bees kept in areas of lower cultivation exhibited higher lipid levels than those kept in areas of high cultivation, but this effect was observed only in colonies that were free of Varroa mites. Furthermore, we found that the presence of mites was associated with lower lipid levels and higher titers of deformed wing virus (DWV), as well as a non-significant trend towards higher overwinter losses. Overall, these results show that mite infestation interacts with landscape, obscuring the effects of landscape alone and suggesting that the benefits of improved foraging landscape could be lost without adequate control of mite infestations.

Differential gene expression of two extreme honey bee (Apis mellifera) colonies showing varroa tolerance and susceptibility.

Varroa destructor, an ectoparasitic mite of honey bees (Apis mellifera), is the most serious pest threatening the apiculture industry. In our honey bee breeding programme, two honey bee colonies showing extreme phenotypes for varroa tolerance/resistance (S88) and susceptibility (G4) were identified by natural selection from a large gene pool over a 6-year period. To investigate potential defence mechanisms for honey bee tolerance to varroa infestation, we employed DNA microarray and real time quantitative (PCR) analyses to identify differentially expressed genes in the tolerant and susceptible colonies at pupa and adult stages. Our results showed that more differentially expressed genes were identified in the tolerant bees than in bees from the susceptible colony, indicating that the tolerant colony showed an increased genetic capacity to respond to varroa mite infestation. In both colonies, there were more differentially expressed genes identified at the pupa stage than at the adult stage, indicating that pupa bees are more responsive to varroa infestation than adult bees. Genes showing differential expression in the colony phenotypes were categorized into several groups based on their molecular functions, such as olfactory signalling, detoxification processes, exoskeleton formation, protein degradation and long-chain fatty acid metabolism, suggesting that these biological processes play roles in conferring varroa tolerance to naturally selected colonies. Identification of differentially expressed genes between the two colony phenotypes provides potential molecular markers for selecting and breeding varroa-tolerant honey bees.

Factors influencing the prevalence and infestation levels of Varroa destructor in honeybee colonies in two highland agro-ecological zones of Uganda.

Varroa mites are ecto-parasites of honeybees and are a threat to the beekeeping industry. We identified the haplotype of Varroa mites and evaluated potential factors that influence their prevalence and infestation levels in the eastern and western highland agro-ecological zones of Uganda. This was done by collecting samples of adult worker bees between December 2014 and September 2015 in two sampling moments. Samples of bees were screened for Varroa using the ethanol wash method and the mites were identified by molecular techniques. All DNA sequences obtained from sampled mite populations in the two zones were 100 % identical to the Korean Haplotype (AF106899). Mean mite prevalence in the apiaries was 40 and 53 % for the western and eastern zones, respectively, during the first sampling. Over the second sampling, mean mite prevalence increased considerably in the western (59 %) but not in the eastern (51 %) zone. Factors that were associated with Varroa mite infestation levels include altitude, nature of apiary slope and apiary management practices during the first sampling. Our results further showed that Varroa mites were spreading from lower to higher elevations. Feral colonies were also infested with Varroa mites at infestation levels not significantly different from those in managed colonies. Colony productivity and strength were not correlated to mite infestation levels. We recommend a long-term Varroa mite monitoring strategy in areas of varying landscape and land use factors for a clear understanding of possible changes in mite infestation levels among African honeybees for informed decision making.

Occurrence and Distribution of Varroa Mite and Antivarroa Effect of Propolis in Walmara District of Oromia Special Zone Around Finfine, Ethiopia

A cross-sectional study was carried out from November, 2014 to April, 2015 aimed to assess the occurrence, infestation rate and associated risk factors of Varroa mite on Honeybees; investigation of the effect of propolis on varroa mites in Walmara District. Purposive sampling was used in Peasant Association; twelve apiaries and sixty four hives were randomly selected for inspection. Interviews, direct observation and experimental set up were the main data collection techniques used to gather the information. The results revealed the whole (384) bee colonies examined for Varroa mites were Positive with varies infestation range 4%-53% in brood and 4%-36% in adult Honeybees. The highest Adult infestation rate 18.20 ± 7.99% of Varroa mites was observed in Tullu Harbu, while the lowest infestation rate (14.25 ± 5.12%) was observed Wajitu Harbu. on other side The highest Brood infestation rate (22.76 ± 9.64) % of Varroa mites was observed in Nano Suba, while the lowest infestation rate 13.73 ± 5.88% was observed Wajitu Harbu. Infestation levels showed significant relationship with colony type (p=0.006). Weak colony type is highly infested than strong colony, However, associated risk factors including age, sex, educational status, duration of experience of Beekeepers, and site and hive type were not showed statistical significance with Varroa mite infestation (P>0.05). Effect of Propolis against Varroa Mite has been investigated and showed lethal effect. Propolis extracted with 70% ethanol was found to be highly toxic, at 20% (w/v) of propolis resulting in 94.44% mortality with a brief contact time of 5 sec. The study showed that whole bee colonies examined were co-existed with the mites and lethal effect of propolis on Varroa mites. Therefore, improved management system and further research to use propolis extract as a treatment option was recommended.

Resistance rather than tolerance explains survival of savannah honeybees (Apis mellifera scutellata) to infestation by the parasitic mite Varroa destructor.

Varroa destructor is considered the most damaging parasite affecting honeybees (Apis mellifera L.). However, some honeybee populations such as the savannah honeybee (Apis mellifera scutellata) can survive mite infestation without treatment. It is unclear if survival is due to resistance mechanisms decreasing parasite reproduction or to tolerance mechanisms decreasing the detrimental effects of mites on the host. This study investigates both aspects by quantifying the reproductive output of V. destructor and its physiological costs at the individual host level. Costs measured were not consistently lower when compared with susceptible honeybee populations, indicating a lack of tolerance. In contrast, reproduction of V. destructor mites was distinctly lower than in susceptible populations. There was higher proportion of infertile individuals and the reproductive success of fertile mites was lower than measured to date, even in surviving populations. Our results suggest that survival of savannah honeybees is based on resistance rather than tolerance to this parasite. We identified traits that may be useful for breeding programmes aimed at increasing the survival of susceptible populations. African honeybees may have benefited from a lack of human interference, allowing natural selection to shape a population of honeybees that is more resistant to Varroa mite infestation.

Parasites and Pathogens of the Honeybee (Apis mellifera) and Their Influence on Inter-Colonial Transmission.

Pathogens and parasites may facilitate their transmission by manipulating host behavior. Honeybee pathogens and pests need to be transferred from one colony to another if they are to maintain themselves in a host population. Inter-colony transmission occurs typically through honeybee workers not returning to their home colony but entering a foreign colony (“drifting”). Pathogens might enhance drifting to enhance transmission to new colonies. We here report on the effects infection by ten honeybee viruses and Nosema spp., and Varroa mite infestation on honeybee drifting. Genotyping of workers collected from colonies allowed us to identify genuine drifted workers as well as source colonies sending out drifters in addition to sink colonies accepting them. We then used network analysis to determine patterns of drifting. Distance between colonies in the apiary was the major factor explaining 79% of drifting. None of the tested viruses or Nosema spp. were associated with the frequency of drifting. Only colony infestation with Varroa was associated with significantly enhanced drifting. More specifically, colonies with high Varroa infestation had a significantly enhanced acceptance of drifters, although they did not send out more drifting workers. Since Varroa-infested colonies show an enhanced attraction of drifting workers, and not only those infected with Varroa and its associated pathogens, infestation by Varroa may also facilitate the uptake of other pests and parasites.

A prismatic view of protein phosphorylation in health and disease.

The paramount relevance of protein phosphorylation in health and disease motivated us to gather several contributions from experts working in this area in order to portray the recent developments in the field. Our effort and the effort of 54 authors with their 12 contributions gave rise to this Research Topic, which represents a valuable forum where phosphorylation is discussed from different angles, including bioinformatics approaches and experimental methods that are currently used to decipher the complex mechanisms underlying this bewitching post-translational modification (PTM). The articles collected in this Research Topic illustrate very diverse aspects of phosphorylation, such as its biological effects and induced structural changes, the role of kinases and phosphatases as therapeutic targets, the use of phosphorylation profiles as biomarkers, how phosphorylation dys-regulation may cause disease, and more.